Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
cam luc » cau luc
sach ly » sach y, sach lo, sach ty
hieu va » lieu va, hieu qua
hieu ve » hieu van
ly hang » ly quang
cuu tre » cua tre, cau tren, cau treo
hang o » hang do, hang o2, hoang o
vi cuu » vi luu, vinh cuu
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ly hang o hoi. ((hieu ve) OR (hieu va)) ((cam luc) or (cam xuc)) va hanh vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ly hang o hoi. ((hieu ve) OR (hieu va)) ((cam luc) OR (cam xuc)) va hanh vi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ly hang o hoi. ((hieu ve) OR (hieu va)) ((cam luc) or (cam xuc)) va hanh vi cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ly hang o hoi. ((hieu ve) OR (hieu va)) ((cam luc) or (cam xuc)) va hanh vi cuu tre*.